The blood feeding patterns of Culiseta melanura, Culiseta morsitans, Coquillettidia perturbans ad several Aedes and species collected in EEE virus foci in Southeastern Massachusetts and central New York State were determined by serology. Late season increases in mammal and mixed mammal-bird feedings were observed in Culiesta melanura, the known enzootic vector, which normally fed largely on passerine birds. Coquillettidia, Aedes and Anopholes species fed mainly on mammals. Culiseta melanura fed mainly during the evening post-sunset period and was as active above the tree canopy as near the ground. Work on the rate of young and virenic animals as natural hosts of arbovirus vectors has been initiated. Methods to collect engorged female black flies are being sought by investigation of dispersal patterns and resting habitat selection. Prosimulium appear to rest in the forest canopy. A permanent laboratory colony of Simullum decorum has been established and is currently in the 8th generation. A large wind tunnel (9 meters long by 2 meters in diameter) is being constructed to study the responses of wild mosquitoes to various visual and olfactory stimuli.